Froth-breaking device



W. O. BORCHERDT.

FROTH BREAKING DEVICE.

APPLICATION FILED Aue.26, 1919.

Patented Apr. 26, 1921.

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FROTH BREAKING DEVICE.

APPLICATION FILED Aue.26, I919.

1,376,073. Patented Apr. 26, 1921.

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WALTER O. B ORCHERDT, 0F AUSTINVILLE, VIRGINIA, ASSIGNOR TO THE NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

FROTH-BREAKING DEVICE.

Specification of Letters Patent Patnted A t 26 1921 Application filed August 26, 1919. Serial No. 319,967.

T 0 all whom it may concem- Be it known that I, WALTER O. BORCHERDT, a citizen of the United States, residing at Austinville, in the county of Wythe, State of Virginia, have invented certain new and useful Improvements in Froth-Breaking Devices; and I do hereby declare the following tobe a full, clear, and exact description of the invention, such as will enable others must be removed therefrom, to permit of "unsatisfactory results. make the use of water sprays undesirable,

the concentration or collection of the substance. forming the froth. As the tonnage of material treated is increased, the .volume of froth naturally increases, and as the froth breaks down more or less slowly consider able difficulty is experienced in handling and transferring it.- Water sprays have heretofore been used to break up the froth, but considerable water is required to do this effectively, and the water must moreover be quite. finely divided and projected against the froth with considerable force. i

- Frequently, so much water must be used in this way that the pulp resulting from breakingdown the froth is too dilute for the next succeeding step in the process, and thickening tanks or other means must be resorted to to restore the desired pulp density, thus introducing additional apparatus requiring mill space and attentionand' entailing additional expense for operation.

spite the expense, to obviate the useof water and consequent undesirable pulp dilution, and in other cases over-capacity centrifugal pumps of. concentrating tables have been employed for this purpose with generally These conditions and it has heretofore been generally customary to break up excessive rushes of froth with a stick in order to avoid the use of too much water.

' 71 have discovered that the froth from flotation operations can be very effectively broken down by a rotating diskrunning in the froth, but not in the pulp resulting from the reliquefied froth, and having such a circumferential velocity that not 'much froth is thrown oil the edge of the disk by centrifugal force. Thus, I have determined that. the circumferential velocity of the disk should not exceed about 1000- feet per minute, and I have found that a circumferential velocity of approximately 800 feet per mlnute gives excellent results. In carrying out the invention the disk may be operatively mounted in any appropriate froth collecting chamber or receptacle, such, for example, as in the froth launders or froth collecting. chambers of the flotation apparatus, or in auxiliary l'aunders or troughsthrough which the froth is transferred. The diskis disposed in a substantially vertical position and is arranged for rotation about a substantially horizontal axis. 7 1

I have, moreover, found that the action of the rotating disk in breaking 'u the froth is materially improved by rou'g ening the surface thereof. Thus, I have found that a disk of rough sheet material, such, for

example, as sheet iron roughened or pitted with perforations, by using a piece of screen cloth to form the disk, or by covering the surface of the disk with bosses or projections', or the disk may be given a corrugated or wavy or otherwise distorted configurav In the accompanying drawings and the following description, I have illustrated and described the best embodiments of my invention of which I am now. aware. In these drawings,+

Figure 1 is a side elevation, partly in section of apneumatic flotation cell embodying the invention;

Fig. 2 is an end view of the apparatus of Fig. 1;

Fig. 3 is a side elevation partly in section of amodified form of cell embodying the invention;

froth outlet 18.

Fig. 4 is a side elevation of a further modified form of flotation cell embodying the Referring to Figs. 1 and 2 of the drawings, there is diagrammatically represented a flotation cell or apparatus 10 of the pneumatic type, such, for example, as the well known Callow cell. launder 11 extending along each side and communicating with a froth collecting chamber 12 at one end of the cell. A disk 13 is operatively mounted in the froth collecting chamber 12, and is disposed in a substantially vertical position and is arranged for rotation about a substantially horizontal axis. In Figs. 1 and 2 of the drawings, I have shown a bracket 14 secured to the outer wall of the froth-collecting chamber 12. A horizontal shaft 15 is rotatably mounted in suitable bearings on the bracket 14 and is adapted to be driven from any suitable source of power by means of a pulley 16. The shaft 15 extends through'a stuffing box 17 into the froth-collecting chamber 12, and the disk 13 is secured to the inner end of the shaft, as indicated in Fig. 1. of the draw- 1n s. pr%vided with an outlet 18 for the liquefied froth.

As it is the purpose of the inve tion to hold the froth in contact with the lsk until Y it is broken down or liquefied, and to secure the prompt removal of the resulting pulp so that the disk may not be caused to run partly immersed in pulp,'which would tend toward reformation of froth, it-may sometimes be desirable to employ'a trap in the pipe 18. Thus, in Fig. 1 of the drawings, I

have indicated a suitable-trap 23 or seal of' any usual kind connected to the liquefied The trap or liquid seal 23 permitsthe discharge of the liquefied pulp as rapidly as it is formed but by maintaining a seal of pulp retains the froth in the froth collecting chamber 12 until it is liquefied.

In Fig. 3 'of the drawings, the rotatably mounted disk 13 is operatively arranged in a froth launder 11 extending alon the side of the flotation apparatus 10. he froth launder 11 slopes from either end toward its middle and at its intermediate or lowest portion is provided with an" outlet 18 for lique-. fied froth. Where the flotation apparatus has a froth launder on each side thereof, it will be understood that a froth breaking disk 13 will be operatively mounted in each launder.

In Fig. 4 of the drawings, I have represented a flotation cell 10" having a sli htly different type of overflow froth launder llf This cell has a froth The froth collecting chamber 12 is ranged so that the discharge of the froth takes place at one end of the flotation cell. The froth breaking disk 13 is operatively mounted for rotation in substantially the deepest part ofthe froth launder 11 and where there is a froth launder on each side of the cell, a froth breakin disk will be arranged in each launder. The launder 11" is provided in its lowermost portion with a liquefied froth outlet 18". In Fig. 4 of the drawings, I have also shown 'a water supply pipe 19 for discharging a jet or-spray of water on the froth breaking 'disk 13, so as to facilitate the breaking down and liquefaction of the froth.

vided for permitting the free passage through the launder of liquefied froth, but which holds back all unbroken froth. 7

If desired, the launder 20 may be provided with a trap or seal having a similar function to the trap 23 of Fig. 1. Thus, a depression or pocket 24 may be formed in the bottom of the launder 20 1n which liquefied pulp collects. Into-this pool the slip gate or partition 22 dips, forming in c'omblnation therewith a trap or seal intended to retain froth in contact with the disk 13 but permitting pulp to flow away as rapidly as formed.

In operating my improved froth breaking device, the speed of the rotating disk 13 should be kept below the point at which inches, in diameter and running at a speed of 80 R. P. M., thereby giving a circumferential velocity of 755 feet per minute. w

p The froth breakingdisk 13 should rotate entirely in froth and not in pulp, and on this account the power required for rotating the disk is very small. The disadvantage of allowing the lower edge of the disk, and generally any portion of the disk, to run in pulp or liquefied froth is that new froth is constantly formed by the impact of themasses of froth on the pulp and'by the rotation of the disk carrying air back into the pulp. 1n operating my improved froth breaking device, I accordingly arrange so that as soon as the froth-is liquefied or again reduced to a pulp, it ,tvill flow away freely,- but that so whichthe disk works.

As previously mentioned, the froth breaking disk is preferably of rough sheet material,as, for example, sheet iron roughened or pitted by rusting. I have found that a rusted iron surface provides an excellent agency for cutting down the gas bubbles in the froth. The roughened surface of the disk may, however, be secured in other ways, and in Fig. 6 of the drawings, I have shown a corrugated disk 13'. The radial ribs produced on each surface of the disk 13' as the result of its corrugated configuration provide suitable projections or protuberances for. assistin in breaking up the gas bubbles in the frot Various expedients for accomplishing this same end will suggest themselves to those skilled in the art and I have mentioned certain specific means for roughening the. surface of the disk merely by way of example. The effect of a roughened surface may also be secured by placing the disk at a slight inclination on the horizontal shaft, so as to produce a side throw or wabble. In practice, this result may be simply obtained by slightly bending the sheet metal of the disk. This modification of the invention is illustrated in Fig. 7

of the drawings, where a pair of froth breaking disks 13" are mounted on the horizontal shaft 15 at a slight inclination to a perpendicular or vertical position. Fig. 7 also illustrates the use of a multiplicity of the froth hereinbefore described forms of the invention. 7

The froth breaking disk may, of course,

be constructed in any suitable sizes and of any appropriate material, although a rusty sheet iron disk will generally be preferable because of its cheapness' and the ease with which it can be prepared for use. I have operated rusty sheet iron disks in various sizes with very excellent results. I have thus found it possible by using the froth breaking device of the invention to very greatly increase the froth output from a given cell over what would otherwise be possible. The volume of pulp resulting from breaking down froth bears about the same relation to the volume of the froth as the volume of water produced by melting snow bears to the volume of the freshly fallen snow. This expanded condition of the froth makes it diflicult to efliciently handle the same and the breaking down of the froth as promptly as possible is a matter of importance, particularly in the handling of large tonnage. The froth breaking device of the invention is of particular advantage in this connection since it can be conveniently applied to the overflow froth launders of the flotation apparatus, where it effectively operates to with a circumferential velocity of less promptly break down the froth and thus enables the cell to be worked harderwith a corresponding increase in its froth output. The froth breaking device of the invention is especially desirable when it becomes necessary to deal with colloid-bearing or over stabilized froths, which in many plants cause serious difliculty in handling and subsequent treatment.

What I claim is:

1. In combination with a flotation apparatus, a froth breaking device comprising a disk mounted for rotation about a substantially horizontal axis.

2. In combination with a flotation apparatus, a froth breaking device comprising a disk disposed in a substantially vertical position and rotating about a substantially horizontal axis with a circumferential velocity of less than 1000 feet per minute.

3. In combination with a flotation apparatus, a froth breaking device comprising a rotating disk disposed in a substantially vertical position and having a circumferential velocity of less than 1000 feet per minute.

4. In combination with a flotation apparatus, a froth breakin device comprising a disk of sheet iron having a surface roughened by rusting mounted for rotation about a substantiallyhorizontal axis.

5. In combination with a flotation appa ratus, a froth breaking device comprising a disk having a roughened surface disposed in a substantially vertical position and ro tating about a substantially horizontal axis than 1000 feet per minute.

6. In combination with a flotation apparatus, a froth collecting chamber having an outlet for liquefied froth, and a froth breaking device comprising a rotating disk operatively mounted in said chamber for rotation about a substantially horizontal axis and having a circumferential velocity of less than 1000 -feet per minute.

'7. In combination with a flotation appa ratus, a froth collecting chamber having an outlet for liquefied froth, and a froth breaking device comprising a disk having a roughened surface operatively mounted in said chamber for rotation about a substan tially horizontal axis.

8. In combination with a flotation appa ratus, a froth breaking device comprislng a disk of sheet iron having a surface rough-- stantially horizontal axis with a circumferential Velocity of less than 1000 feet per minute.

10." In combination with a flotation apparatus, a froth collecting chamber'having an outlet for liquefied froth, a liquid seal operatively associated with said outlet 'for retaining the froth in said chamber while permitting liquefied froth tmfiow away therefrom, and a froth breaking device comprising a rotating disk operatively mounted in said chamber for rotation about a substantially horizontal axis.

In testimony whereof I aflix my signature.

WALTER o. BORGHEBDT. 

